RFID technology generally involves interrogating an RFID tag with radio frequency (RF) waves and reading the responding RF waves with an RFID reader. An RFID tag typically includes a miniscule microchip coupled to an RF antenna. RFID tags can be attached to the object to be identified. An RFID reader typically includes an antenna coupled to a transmitter and a receiver. The RFID reader is generally associated with some read zones, and only those RFID tags located within the read zones are read by the RFID reader. A user generally may not know the boundaries of the read zones, because the field strengths of the RF waves at different locations are not readily visible. Accordingly, it is desirable to find a method or apparatus that can provide some good visual aid to the boundaries of the read zones of RFID readers.